organic compounds
[(1S,2S,3R,4R)-3-Hydroxy-4,7,7-trimethylbicyclo[2.2.1]heptan-2-yl]methyl[(E)-3-(trimethylsilyl)prop-2-enyl]selenonium bromide
aSchool of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, People's Republic of China, and bState Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, People's Republic of China
*Correspondence e-mail: llyyjz@nju.edu.cn
The title compound, a selenonium bromide, C17H33OSeSi+·Br−, was obtained from the reaction of enantiomerically pure 4,7,7-trimethyl-2-methylselanylbicyclo[2.2.1]heptan-3-ol and (3-bromopropenyl)trimethylsilane in acetone. Due to the chiral bicyclic substituent, the is not centrosymmetric and has no symmetry plane, with four chiral C atoms in the cation. The contains one selenonium cation and one bromide anion. C–H⋯Br and O–H⋯Br hydrogen bonds link the ions, forming a one-dimensional R-helical chain-like supramolecular structure.
Related literature
For related literature, see: Li et al. (2005); Goodridge et al. (1988); Reich et al. (1975); Ye et al. (2002).
Experimental
Crystal data
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Data collection: SMART (Bruker, 2000); cell SMART; data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
10.1107/S1600536808016863/im2070sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808016863/im2070Isup2.hkl
A solution of 4,7,7-trimethyl-2-methylselanyl-bicyclo[2.2.1]heptan-3-ol (1) (2.4 g, 9.7 mmol) and (3-bromo-propenyl)-trimethylsilane (3) (1.9 g, 9.7 mmol) in acetone (5 mL) was stirred at 273 K. The solid was collected and washed with ethyl ether to afford the selenonium salt (2) in 91% yield. Single crystals of (2) were obtained by slow evaporation from 10 mL of a methanolic solution containing 50 mg (2).
H atoms bonded to O atoms were located in a difference map and refined with distance restraints of O—H = 0.87 (10), and with Uiso(H) = 1.2Ueq(O). Other H atoms were positioned geometrically and refined using a riding model (including
about the ethanol C—C bond), with C—H = 0.96–0.98 Å and with Uiso(H) = 1.2(1.5 for methyl groups) times Ueq(C).Data collection: SMART (Bruker, 2000); cell
SMART (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).C17H33OSeSi+·Br− | F(000) = 452 |
Mr = 440.39 | Dx = 1.366 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 895 reflections |
a = 7.555 (2) Å | θ = 2.1–24.5° |
b = 10.023 (2) Å | µ = 3.67 mm−1 |
c = 14.423 (3) Å | T = 291 K |
β = 101.29 (3)° | Bloc, colourless |
V = 1071.0 (4) Å3 | 0.30 × 0.26 × 0.24 mm |
Z = 2 |
Bruker SMART Apex CCD diffractometer | 3374 independent reflections |
Radiation source: sealed tube | 1732 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
phi and ω scans | θmax = 26.0°, θmin = 1.4° |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −9→9 |
Tmin = 0.35, Tmax = 0.41 | k = 0→12 |
4460 measured reflections | l = 0→17 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.053 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.102 | w = 1/[σ2(Fo2) + (0.046P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.07 | (Δ/σ)max < 0.001 |
3374 reflections | Δρmax = 0.64 e Å−3 |
170 parameters | Δρmin = −0.74 e Å−3 |
1 restraint | Absolute structure: Flack (1983), 1140 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.01 (2) |
C17H33OSeSi+·Br− | V = 1071.0 (4) Å3 |
Mr = 440.39 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 7.555 (2) Å | µ = 3.67 mm−1 |
b = 10.023 (2) Å | T = 291 K |
c = 14.423 (3) Å | 0.30 × 0.26 × 0.24 mm |
β = 101.29 (3)° |
Bruker SMART Apex CCD diffractometer | 3374 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | 1732 reflections with I > 2σ(I) |
Tmin = 0.35, Tmax = 0.41 | Rint = 0.035 |
4460 measured reflections |
R[F2 > 2σ(F2)] = 0.053 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.102 | Δρmax = 0.64 e Å−3 |
S = 1.07 | Δρmin = −0.74 e Å−3 |
3374 reflections | Absolute structure: Flack (1983), 1140 Friedel pairs |
170 parameters | Absolute structure parameter: 0.01 (2) |
1 restraint |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.32321 (7) | 1.05851 (10) | 0.09364 (5) | 0.0584 (2) | |
C1 | 0.6248 (8) | 0.4347 (6) | 0.3285 (4) | 0.0404 (14) | |
H1A | 0.6335 | 0.3442 | 0.3079 | 0.061* | |
H1B | 0.5363 | 0.4400 | 0.3679 | 0.061* | |
H1C | 0.7399 | 0.4630 | 0.3637 | 0.061* | |
C2 | 0.7389 (6) | 0.5504 (10) | 0.2095 (4) | 0.0425 (13) | |
H2A | 0.8154 | 0.6083 | 0.2529 | 0.064* | |
H2B | 0.7085 | 0.5928 | 0.1488 | 0.064* | |
H2C | 0.8013 | 0.4683 | 0.2036 | 0.064* | |
C3 | 0.5706 (8) | 0.5219 (6) | 0.2454 (5) | 0.0498 (18) | |
C4 | 0.4232 (11) | 0.4559 (8) | 0.1682 (5) | 0.0445 (19) | |
H4 | 0.4615 | 0.3724 | 0.1428 | 0.053* | |
C5 | 0.3867 (6) | 0.5695 (8) | 0.0960 (4) | 0.0361 (12) | |
H5 | 0.4822 | 0.5710 | 0.0588 | 0.043* | |
C6 | 0.3996 (9) | 0.6917 (8) | 0.1552 (5) | 0.0398 (16) | |
H6 | 0.4963 | 0.7496 | 0.1422 | 0.048* | |
C7 | 0.4459 (9) | 0.6398 (7) | 0.2553 (4) | 0.0473 (15) | |
C8 | 0.2804 (6) | 0.5707 (9) | 0.2761 (4) | 0.0406 (14) | |
H8A | 0.1744 | 0.6264 | 0.2578 | 0.049* | |
H8B | 0.2955 | 0.5499 | 0.3428 | 0.049* | |
C9 | 0.2627 (8) | 0.4411 (7) | 0.2161 (5) | 0.0460 (15) | |
H9A | 0.2728 | 0.3619 | 0.2555 | 0.055* | |
H9B | 0.1499 | 0.4384 | 0.1704 | 0.055* | |
C10 | 0.5215 (9) | 0.7500 (7) | 0.3273 (5) | 0.047 | |
H10A | 0.6407 | 0.7741 | 0.3196 | 0.071* | |
H10B | 0.5262 | 0.7175 | 0.3903 | 0.071* | |
H10C | 0.4444 | 0.8269 | 0.3166 | 0.071* | |
C11 | 0.2014 (9) | 0.3828 (7) | −0.0510 (5) | 0.043 | |
H11A | 0.3020 | 0.3955 | −0.0816 | 0.064* | |
H11B | 0.0971 | 0.3576 | −0.0970 | 0.064* | |
H11C | 0.2294 | 0.3137 | −0.0043 | 0.064* | |
C12 | 0.2030 (8) | 0.6908 (7) | −0.0809 (4) | 0.0415 (15) | |
H12A | 0.1683 | 0.7780 | −0.0614 | 0.050* | |
H12B | 0.3310 | 0.6926 | −0.0820 | 0.050* | |
C13 | 0.0925 (8) | 0.6561 (7) | −0.1810 (4) | 0.0430 (15) | |
H13 | −0.0322 | 0.6663 | −0.1918 | 0.052* | |
C14 | 0.1643 (8) | 0.6141 (6) | −0.2502 (4) | 0.0385 (13) | |
H14 | 0.2893 | 0.6068 | −0.2395 | 0.046* | |
C15 | −0.0572 (9) | 0.3993 (7) | −0.3683 (5) | 0.047 | |
H15A | −0.1696 | 0.4027 | −0.3468 | 0.071* | |
H15B | 0.0262 | 0.3436 | −0.3267 | 0.071* | |
H15C | −0.0771 | 0.3631 | −0.4311 | 0.071* | |
C16 | −0.1393 (8) | 0.6949 (7) | −0.4057 (5) | 0.041 | |
H16A | −0.2022 | 0.6764 | −0.4689 | 0.061* | |
H16B | −0.0837 | 0.7813 | −0.4039 | 0.061* | |
H16C | −0.2231 | 0.6937 | −0.3636 | 0.061* | |
C17 | 0.1943 (7) | 0.5796 (7) | −0.4543 (4) | 0.049 | |
H17A | 0.2631 | 0.4987 | −0.4522 | 0.073* | |
H17B | 0.2746 | 0.6536 | −0.4372 | 0.073* | |
H17C | 0.1259 | 0.5926 | −0.5171 | 0.073* | |
O1 | 0.2297 (6) | 0.7626 (5) | 0.1376 (3) | 0.0473 (11) | |
H1D | 0.248 (10) | 0.845 (8) | 0.125 (5) | 0.057* | |
Se1 | 0.15165 (6) | 0.54982 (7) | 0.01059 (4) | 0.04094 (15) | |
Si1 | 0.03564 (18) | 0.5673 (2) | −0.36882 (11) | 0.0395 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0503 (3) | 0.0494 (4) | 0.0775 (5) | −0.0034 (4) | 0.0172 (3) | −0.0074 (5) |
C1 | 0.043 (3) | 0.043 (4) | 0.040 (3) | 0.000 (3) | 0.020 (3) | 0.000 (3) |
C2 | 0.031 (2) | 0.049 (3) | 0.043 (3) | −0.012 (4) | −0.0060 (19) | −0.021 (5) |
C3 | 0.038 (3) | 0.046 (4) | 0.053 (4) | −0.019 (3) | −0.020 (3) | 0.003 (3) |
C4 | 0.059 (4) | 0.038 (4) | 0.034 (4) | −0.005 (3) | 0.004 (3) | 0.008 (3) |
C5 | 0.035 (2) | 0.037 (3) | 0.035 (3) | 0.019 (3) | 0.0062 (18) | 0.005 (3) |
C6 | 0.034 (3) | 0.048 (4) | 0.040 (4) | −0.005 (3) | 0.013 (3) | 0.003 (3) |
C7 | 0.052 (3) | 0.047 (3) | 0.037 (4) | 0.001 (3) | −0.003 (3) | 0.006 (3) |
C8 | 0.042 (2) | 0.049 (4) | 0.035 (3) | 0.016 (3) | 0.017 (2) | −0.009 (3) |
C9 | 0.034 (3) | 0.046 (4) | 0.055 (4) | −0.004 (3) | 0.004 (3) | 0.005 (3) |
C10 | 0.049 | 0.049 | 0.049 | 0.000 | 0.021 | 0.000 |
C11 | 0.044 | 0.044 | 0.044 | 0.000 | 0.018 | 0.000 |
C12 | 0.039 (3) | 0.051 (4) | 0.036 (3) | 0.020 (3) | 0.012 (3) | 0.009 (3) |
C13 | 0.045 (3) | 0.048 (4) | 0.033 (3) | 0.005 (3) | 0.002 (3) | 0.014 (3) |
C14 | 0.044 (3) | 0.044 (3) | 0.029 (3) | −0.004 (2) | 0.012 (2) | −0.002 (3) |
C15 | 0.049 | 0.049 | 0.049 | 0.000 | 0.021 | 0.000 |
C16 | 0.043 | 0.043 | 0.043 | 0.000 | 0.020 | 0.000 |
C17 | 0.050 | 0.050 | 0.050 | 0.000 | 0.020 | 0.000 |
O1 | 0.046 (2) | 0.049 (3) | 0.038 (2) | −0.010 (2) | −0.0126 (19) | 0.003 (2) |
Se1 | 0.0358 (2) | 0.0516 (3) | 0.0339 (3) | 0.0028 (4) | 0.00292 (19) | 0.0086 (4) |
Si1 | 0.0420 (7) | 0.0402 (9) | 0.0380 (8) | 0.0077 (9) | 0.0119 (6) | −0.0030 (10) |
Br1—O1 | 3.143 (5) | C10—H10B | 0.9600 |
C1—C3 | 1.475 (9) | C10—H10C | 0.9600 |
C1—H1A | 0.9600 | C11—Se1 | 1.965 (7) |
C1—H1B | 0.9600 | C11—H11A | 0.9600 |
C1—H1C | 0.9600 | C11—H11B | 0.9600 |
C2—C3 | 1.492 (8) | C11—H11C | 0.9600 |
C2—H2A | 0.9600 | C12—C13 | 1.560 (9) |
C2—H2B | 0.9600 | C12—Se1 | 2.022 (6) |
C2—H2C | 0.9600 | C12—H12A | 0.9700 |
C3—C7 | 1.535 (9) | C12—H12B | 0.9700 |
C3—C4 | 1.559 (9) | C13—C14 | 1.295 (8) |
C4—C9 | 1.515 (10) | C13—H13 | 0.9300 |
C4—C5 | 1.531 (10) | C14—Si1 | 1.855 (6) |
C4—H4 | 0.9800 | C14—H14 | 0.9300 |
C5—C6 | 1.484 (10) | C15—Si1 | 1.825 (7) |
C5—Se1 | 1.963 (5) | C15—H15A | 0.9600 |
C5—H5 | 0.9800 | C15—H15B | 0.9600 |
C6—O1 | 1.446 (8) | C15—H15C | 0.9600 |
C6—C7 | 1.510 (9) | C16—Si1 | 1.842 (7) |
C6—H6 | 0.9800 | C16—H16A | 0.9600 |
C7—C8 | 1.510 (9) | C16—H16B | 0.9600 |
C7—C10 | 1.546 (9) | C16—H16C | 0.9600 |
C8—C9 | 1.552 (10) | C17—Si1 | 1.884 (5) |
C8—H8A | 0.9700 | C17—H17A | 0.9600 |
C8—H8B | 0.9700 | C17—H17B | 0.9600 |
C9—H9A | 0.9700 | C17—H17C | 0.9600 |
C9—H9B | 0.9700 | O1—H1D | 0.87 (8) |
C10—H10A | 0.9600 | ||
C3—C1—H1A | 109.5 | C7—C10—H10A | 109.5 |
C3—C1—H1B | 109.5 | C7—C10—H10B | 109.5 |
H1A—C1—H1B | 109.5 | H10A—C10—H10B | 109.5 |
C3—C1—H1C | 109.5 | C7—C10—H10C | 109.5 |
H1A—C1—H1C | 109.5 | H10A—C10—H10C | 109.5 |
H1B—C1—H1C | 109.5 | H10B—C10—H10C | 109.5 |
C3—C2—H2A | 109.5 | Se1—C11—H11A | 109.5 |
C3—C2—H2B | 109.5 | Se1—C11—H11B | 109.5 |
H2A—C2—H2B | 109.5 | H11A—C11—H11B | 109.5 |
C3—C2—H2C | 109.5 | Se1—C11—H11C | 109.5 |
H2A—C2—H2C | 109.5 | H11A—C11—H11C | 109.5 |
H2B—C2—H2C | 109.5 | H11B—C11—H11C | 109.5 |
C1—C3—C2 | 106.0 (5) | C13—C12—Se1 | 108.2 (4) |
C1—C3—C7 | 117.3 (6) | C13—C12—H12A | 110.1 |
C2—C3—C7 | 117.8 (6) | Se1—C12—H12A | 110.1 |
C1—C3—C4 | 112.0 (5) | C13—C12—H12B | 110.1 |
C2—C3—C4 | 111.8 (6) | Se1—C12—H12B | 110.1 |
C7—C3—C4 | 91.6 (5) | H12A—C12—H12B | 108.4 |
C9—C4—C5 | 109.2 (6) | C14—C13—C12 | 123.8 (5) |
C9—C4—C3 | 103.9 (6) | C14—C13—H13 | 118.1 |
C5—C4—C3 | 100.3 (5) | C12—C13—H13 | 118.1 |
C9—C4—H4 | 114.0 | C13—C14—Si1 | 124.7 (5) |
C5—C4—H4 | 114.0 | C13—C14—H14 | 117.6 |
C3—C4—H4 | 114.0 | Si1—C14—H14 | 117.6 |
C6—C5—C4 | 103.8 (5) | Si1—C15—H15A | 109.5 |
C6—C5—Se1 | 113.2 (4) | Si1—C15—H15B | 109.5 |
C4—C5—Se1 | 111.9 (5) | H15A—C15—H15B | 109.5 |
C6—C5—H5 | 109.3 | Si1—C15—H15C | 109.5 |
C4—C5—H5 | 109.3 | H15A—C15—H15C | 109.5 |
Se1—C5—H5 | 109.3 | H15B—C15—H15C | 109.5 |
O1—C6—C5 | 110.4 (5) | Si1—C16—H16A | 109.5 |
O1—C6—C7 | 111.6 (5) | Si1—C16—H16B | 109.5 |
C5—C6—C7 | 104.1 (6) | H16A—C16—H16B | 109.5 |
O1—C6—H6 | 110.2 | Si1—C16—H16C | 109.5 |
C5—C6—H6 | 110.2 | H16A—C16—H16C | 109.5 |
C7—C6—H6 | 110.2 | H16B—C16—H16C | 109.5 |
C6—C7—C8 | 107.5 (5) | Si1—C17—H17A | 109.5 |
C6—C7—C3 | 102.0 (5) | Si1—C17—H17B | 109.5 |
C8—C7—C3 | 102.2 (5) | H17A—C17—H17B | 109.5 |
C6—C7—C10 | 112.5 (6) | Si1—C17—H17C | 109.5 |
C8—C7—C10 | 114.0 (6) | H17A—C17—H17C | 109.5 |
C3—C7—C10 | 117.4 (5) | H17B—C17—H17C | 109.5 |
C7—C8—C9 | 105.0 (5) | C6—O1—Br1 | 105.8 (4) |
C7—C8—H8A | 110.8 | C6—O1—H1D | 109 (5) |
C9—C8—H8A | 110.8 | C5—Se1—C11 | 98.0 (3) |
C7—C8—H8B | 110.8 | C5—Se1—C12 | 94.2 (3) |
C9—C8—H8B | 110.8 | C11—Se1—C12 | 102.9 (3) |
H8A—C8—H8B | 108.8 | C15—Si1—C16 | 112.8 (3) |
C4—C9—C8 | 100.5 (5) | C15—Si1—C14 | 111.2 (3) |
C4—C9—H9A | 111.7 | C16—Si1—C14 | 107.9 (3) |
C8—C9—H9A | 111.7 | C15—Si1—C17 | 110.9 (3) |
C4—C9—H9B | 111.7 | C16—Si1—C17 | 106.1 (3) |
C8—C9—H9B | 111.7 | C14—Si1—C17 | 107.6 (3) |
H9A—C9—H9B | 109.4 |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1D···Br1 | 0.87 (8) | 2.28 (8) | 3.143 (5) | 175 (7) |
C5—H5···Br1i | 0.98 | 2.88 | 3.827 (5) | 164 |
C11—H11C···Br1ii | 0.96 | 2.94 | 3.874 (7) | 165 |
C12—H12B···Br1i | 0.97 | 2.97 | 3.855 (5) | 152 |
Symmetry codes: (i) −x+1, y−1/2, −z; (ii) x, y−1, z. |
Experimental details
Crystal data | |
Chemical formula | C17H33OSeSi+·Br− |
Mr | 440.39 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 291 |
a, b, c (Å) | 7.555 (2), 10.023 (2), 14.423 (3) |
β (°) | 101.29 (3) |
V (Å3) | 1071.0 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 3.67 |
Crystal size (mm) | 0.30 × 0.26 × 0.24 |
Data collection | |
Diffractometer | Bruker SMART Apex CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2000) |
Tmin, Tmax | 0.35, 0.41 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4460, 3374, 1732 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.616 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.102, 1.07 |
No. of reflections | 3374 |
No. of parameters | 170 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.64, −0.74 |
Absolute structure | Flack (1983), 1140 Friedel pairs |
Absolute structure parameter | 0.01 (2) |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1D···Br1 | 0.87 (8) | 2.28 (8) | 3.143 (5) | 175 (7) |
C5—H5···Br1i | 0.98 | 2.88 | 3.827 (5) | 163.5 |
C11—H11C···Br1ii | 0.96 | 2.94 | 3.874 (7) | 164.5 |
C12—H12B···Br1i | 0.97 | 2.97 | 3.855 (5) | 152.0 |
Symmetry codes: (i) −x+1, y−1/2, −z; (ii) x, y−1, z. |
Acknowledgements
We thank the National Natural Science Foundation of China for its financial support of projects 20332050 and 20572042
References
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Recently, an efficient asymmetric synthesis of cyclopropanes via camphor-derived sulfonium ylides was reported (Ye et al., 2002). Thus, we expected that camphor-derived selenonium ylides could be used in the highly enantioselective synthesis of cyclopropanes, epoxides and aziridines. First, the camphor-derived selenide (1) was prepared from commercially available D-camphor according to a literature method (Reich et al., 1975; Goodridge et al., 1988, and Li et al., 2005). Then compound (1) was reacted with (3-bromo-propenyl)-trimethylsilane (3) to give the selenonium salt (2). We performed the X-ray crystallographic analysis of (2) in order to elucidate the conformation and configuration.
The structural analysis shows that the selenonium ion of the title compound, (2) (Fig. 1), is not centrosymmetric and has no symmetry plane, showing the four chiral C atoms, C4, C5, C6, and C7, with the R, R, S, and S configuration preserved from the enatiomerically pure starting compound (1). The asymmetric unit contains one selenonium salt cation, and one bromide ion. In the crystal packing, the Br atom plays an important role, acting as a bridge linking neighboring molecules via C–H···Br and O–H···Br hydrogen bonds (O1—H1D···Br1, C5—H5···Br1ii, C11—H11c···Br1i, and C12—H12B···Br1ii; symmetry code i: x,-1 + y,z; ii: 1 - x,-1/2 + y, -z), forming a one dimensional R-helical chains-like structure along [010] axis (Fig. 2).